The long-range objective of this proposal is further improvement in the treatment of cancer in children through the participation of investigators at the Vanderbilt University School of Medicine in Children Cancer Group (CCS). The multi-disciplinary team of investigators from Vanderbilt are pooling resources with comparable teams from other institutions to investigate the biology, treatment, and epidemiology of the childhood cancers. Specific aims can be summarized in terms of Vanderbilt's contributions to the Group's scientific endeavors and administrative leadership. These include the following: 1. Through participation in disease-specific Strategy Groups, establish research priorities and develop new strategies for therapeutic studies of acute lymphocytic leukemia (ALL), Hodgkin's disease, neuroblastoma, bone sarcomas, and brain tumors. 2. Through Study Committee chairmanships, provide leadership in the development, conduct, analysis, and reporting of investigation dealing with the treatment of ALL, neuroblastoma, and brain tumors. 3. Through participation as Study Committee members, assist in the conduct of studies concerned with the treatment of ALL, Hodgkin's disease, astrocytoma, and brain stem tumors. 4. Provide leadership in the development and interpretation of studies that assess the developmental and neuropsychologic sequelae of curative therapy for ALL. 5. Through committee participation, contribute to the development and analyses of investigational drugs. 6. Provide administrative leadership through participation on the Executive Committee, the Officers Committee, and the Affiliate Activities Steering Committee. In addition, investigators will continue to enlist the participation of Vanderbilt patients in CCG research protocols so as to facilitate the expeditious conduct and timely conclusion of Group studies.